(RxWiki News) Millions of Americans are affected by asthma. New information on how the age of onset can affect future symptoms may help to improve treatment.
A recent study found that people who developed asthma between 5 and 9 years old had the fewest number of symptoms, attacks and emergency room visits, compared to people who developed asthma before the age of 1 who reported having symptoms the most often and intensely.
People who developed asthma after the age of 10 reported generally less frequent and milder symptoms.
There was little difference between all the age groups ranging from 10 years to 99 years.
These findings suggest that the age when people develop asthma may be related to future symptoms and attacks. The researchers believe this is partly due to how and when a patient learns to manage their asthma.
"Tell your doctor about your history with asthma."
The lead author of this study was Maria C. Mirabelli, MPH, PhD, from the Air Pollution and Respiratory Health Branch of the Division of Environmental Hazards and Health Effects at the National Center for Environmental Health of the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.
The participant data was from a 2010 nationwide survey called the BRFSS Asthma Call-Back survey, and included 12,216 men and women with active asthma who reported being told by a healthcare professional that they had asthma. All the participants were between 18 and 99 years old, 74 percent were female and 80 percent were white.
A total of 42 percent of the participants reported having onset of asthma before the age of 16; the average age of onset in this subgroup of participants was 7 years old. For the participants who reported onset after 16 years old, the average age was 38 years old.
A total of 42 percent reported a history of lung disease, 11 percent reported a history of heart disease, and 49 percent reported no history of smoking.
The researchers found that the lowest frequency of asthma symptoms occurred in the group that reported asthma onset between 5 and 9 years old. Only 21 percent of this group had experienced symptoms in the previous 30 days, and only 8 percent reported symptoms that kept them from sleeping.
The findings also showed that the participants who reported onset before the age of 1 experienced symptoms the most often out of any other group — with 39 percent reporting symptoms in the previous 30 days, and 19 percent reporting symptoms that kept them from sleeping.
In addition, the researchers discovered that the number of asthma attacks, emergency room or urgent care visits and overnight hospital stays in the previous 12 months significantly decreased as the age of onset increased for the participants who experienced onset before the age of 10.
There was very little difference in any of the 12-month outcomes reported in the participants with onset after the age of 10.
Of the participants who reported onset before the age of 15, the frequency and severity of asthma symptoms, attacks and emergency visits were the highest for those who had onset before the age of 1.
The researchers believe that these findings indicated that age of asthma onset is closely associated with how often and severe a patient’s asthma symptoms and attacks will be throughout life.
Among the participants with onset after age 50, there were small increases in symptoms per month and intensity of the symptoms for a few of the age groups.
The researchers believe that these small increases were possibly due to co-occurring conditions in older adults that already affected their health and/or a lower ability to manage asthma for those who had just been diagnosed.
The researchers suggested that these findings can help medical professionals better understand how the age of onset can affect the use of medication, help identify and avoid symptom triggers and influence early communication between patients and doctors.
The researchers wrote that the younger participants who had onset between 5 and 9 (the group with the lowest frequency and severity of symptoms in this study) most likely were taught very early on how to manage their symptoms better than the other age groups.
However, the researchers maintained that more research is needed before they can come to any definite conclusions.
The authors noted some limitations of their study.
First, their data was from a past survey, so specific details from the participants were not available. Second, the data was self-reported, so the researchers could not verify the information.
Third, the data could be biased because people with mild asthma may not have been motivated to participate in the survey. Therefore, adults with mild asthma may have been underrepresented.
Fourth, the participants who reported asthma onset early in childhood may have not reported the onset age accurately.
Lastly, the reported co-occurring conditions could have disproportionately affected participants’ asthma-attributed outcomes.
"This is an interesting study that relied upon The BRFSS Asthma Call Back survey which examined over 12,000 active asthma sufferers between 18 and 99 years of age, specifically exploring the age of asthma onset and its association with asthma control," explained John Oppenheimer, MD, physician at Pulmonary and Allergy Associates in New Jersey.
"The authors found that subjects who reported onset of asthma before the age of 1 experienced the most frequent symptoms. Likewise, the frequency of asthma attacks, acute care visits and hospitalizations decreased as the age of asthma onset increased for those who began suffering from asthma before age 10," Dr. Oppenheimer said.
"As noted by the investigators, this study does have some potential flaws, including: the fact that this is a survey that is missing some potential data that could be helpful, is based upon self-reported information, with potential bias for under representation of mild asthmatics. Understanding these potential flaws, the study still leaves us with important information — that being that the age of asthma onset may determine the diseases severity in later life," he said.
This study was published online in the October edition of Respiratory Medicine.
The National Asthma Control Program in the Air Pollution and Respiratory Health Branch of the National Center for Environmental Health provided funding for this study.
